How intrusive is Timesheet plugin in JIRA?

Is it mainly using already stored data in database, or is it building/creating a lot of tables on it own to store this data?

Does the functionality differs for issues created before/after the plugin is installed?

Instructions

It’s NOT intrusive at all.

It mainly just reads Time Tracking and Issues data stored in Jira database. In case of Jira Server it creates additional table to store scheduled job configurations only.

No functionality differs for issues created before/after the plugin is installed, i.e, no Jira functionality is modified or substituted.